John a



UNITED STATES PATENT OFFICE.

JOHN A. DALY, OF WASHINGTON, DISTRICT OF COLUMBIA.

COATING RUBBER WITH METAL.

SPECIFICATION formingpart of Letters Patent No. 233,144, dated October 12, 1880.

Application filed June 7, 1880. (No model.)

To all whom it may concern:

Be it known that I, JOHN A. DALY, a citizen of the United States, residing at Washington, in the county of Washington and District of Columbia, have invented certain new and useful Improvements in the Art of Uniting a Coating of Metal with Vulcanite Rubber for Dental and other Purposes; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The object of my invention is to so unite a coating of gold or other metal with a plate of vulcanized rubber that it will firmly adhere thereto, and the method by which this is accomplished will be fully hereinafter described, and my special improvements pointed out in the claims.

Attempts have heretofore been made to cover or line vulcanite dental plates with a coating or foil of gold; but these experiments have failed of practically useful results, for the reason, as I believe, that the foil, having a smooth finished surface, will not adhere to the rubber, even if the rubber be vulcanized on the foil, as has been tried.

My improvement enables me to produce a dental vulcanite plate covered or lined to any desired extent with a gold or other metal plate of any desired thickness, so firmly united that it will be. impossible to separate the two by ordinary mechanical means. Usually the part lined will be that which comes in contact with the mouth, so that no poisonous or other ill effect may result from the use of rubber.

I will now proceed to describe one mode of producing a gold-lined dental vulcanite plate.

I take an ordinary plaster model or mold of the mouth, (with or without the teeth attached to said model,) and saturate the plaster with hot wax, by immersion or otherwise, to make the plaster water-repellent. This step does not deform the model in any particular. I then dust or polish this model with graphite, in the ordinary manner of electroplaters, at such parts as I desire to cover with gold. I then hang the model in a gold solution, and by the use of a battery produce an electrodeposit on the coating of the graphite. When the gold film has been deposited to a sufficient thickness I remove the model from the battery and place it in a flask for vulcanizing, and put in rubber for vulcanization, in the usual manner, and proceed to vulcanize the plate just as if there were no electro-deposit of gold on the model. When the vulcanized plate is taken from the flask the gold film will be found firmly attached to the plate, and cannot be removed therefrom by ordinary mechanical means, but adheres as firmly as if plated on a metal.

The method I have described is one which departs very little from the ordinary processes -of dentistry. It will be readily understood,

however, that the method may be varied in many particulars without departing from the spirit of my invention. For instance, many substances other than plaster may be used for a model. I have found litharge to answer a good purpose, and when this is used the treatment with wax may be dispensed with. I do not, however, in this application, claim a dental model made of litharge, as I reserve the right to claim that in a separate application.

Bronze or substances common in the electroplaters art may be used instead of graphite for coating the model.

Nickel, platinum, and other metals may be used instead of gold to form the coating. Silver does not answer a good purpose, because it is attacked by the sulphur in the vulcanite.

When gold is used it need not be so fine as the pure gold usually employed in dentistry. I have found gold of eighteen carats to do well, and this fineness is generally sufficient to resist acids of food and of the stomach.

My gold solution (cyanide of potassium and gold dissolved in nitromuriatic acid) can be used cold when a plaster model is employed; but with models which do not require to be saturated with wax it may be used hot, if desired.

Articles of vulcanite jewelry may be coated with metal in the same way as the dental plates hereinbefore described.

There is a radical difi'erence between my method hereinbefore described and the ordinary method of electroplating on a material which is a non-conductor of electricity. Where an electro-deposit is made in the ordinary way the surface of the non-conductor is coated with graphite or similar substance and the electrodeposit made thereomleaving the graphite between the film and the base. This would be very objectionable ih dental plates; besides, I have found by experiment that gold will not adhere to dental plates when deposited in this way sufficiently to secure good results. Again,

the fit of a dental plate made in this way would not be so good as one made by my process hereinbefore described, as the gold film made by my process is made on the model, and not on the completed plate. So in jewelry. fine lines will be preserved by my method which would be more or less lost it the metal were deposited on the completed vnlcanite base.

I am aware that dental vulcanite plates have been made, or attempted to be made, with a metallic lining by placing a piece of gold or other foil on the model and vulcanizing the rubber upon such foil. This method does not give good results, for the reason that the foil will not adhere firmly to the rubber, owing, as I believe, to the lack of porosity in the foil; nor can the foil be made to fit the model so nicely as an electro-deposit thereon.

What I claim is- 1. The method herein described of making articles of \ulcanite rubber with metallic surfaces, which consists in first coating a mold with metal by electro-deposition and then vulcanizing the rubber on said metal, substantially as set forth.

2. The method of making dental vulcanite plates with metallic surfaces, which consists in first coating the mold with metal by electrodepositon and then vulcanizing the rubber plate on said metal, substantially as set forth.

3. The method herein described of making dental vulcanite plates with metallic surfaces, which consists in first saturating a plaster-ofparis mold with wax, then obtaining an electro-depositthereon, and afterward vulcanizing the rubber plate on said metal, substantially as set forth.

4. A dental vulcanite plate having its surface partly covered with an electro-deposit of metal without any intervening substance between the clectro-plate and the rubber plate, substantially such as described.

In testimony whereof I afiix my signature in presence of two witnesses.

JOHN A. DALY. Witnesses FREDERICK F. DALY, M. P. (JALLAN. 

